Standard 80 Series with 3F petrol/gas - OK?

I'm in the market for a family 4x4 wagon to replace my Series 2A landrover which while it has a certain charm doesnt have the level of safety and on-road (or off road) comfort for my growing family. I was primarily seeking a 4.2 Diesel GQ Patrol but came accross a 1991 80 series petrol Standard Wagon with 225000 km for $14,500. Its a private sale, one lady owner for the last 5 years. Its a 3F petrol with an lpg conversion. Until I saw this vehicle, I wasnt even aware that some Standards came with a petrol motor. Its definitly a Standard, Vinyl front bench seat, rear barn doors, part time 4WD, white paint, no flares, no tacho etc. I know the 3F has a reputation for being thirsty but the lady selling it says she gets about 300km from the 70 litre lpg tank which considering the price of gas (39 cpl) would be slightly better or about the same as diesel economy. The lpg tank has replaced the main tank and the sub tank remains. It seems to drive well, (similar torque to the patrol/cruiser diesels but better pickup) and I cant see any rust. There's a slight whine in 5th gear under load and the change to second and third is notchy and requires a bit of effort on the lever, but I wouldnt describe it as a 'crunch'. It will be used primarily for beach work and towing my camper trailer and 14' tinny. I suspect the petrol will probably go better on the beach than than a diesel? Some comments on whether this vehicle seems like good value would be appreciated. On my budget I'm restricted to high mileage diesels and I'm somewhat worried by the potential cost if something goes wrong with a diesel.